UC1843A

T H E I N F I N I T E P O W E R O F I N N O VAT I O N L I N D O C #: 1840 UC184xA/284xA/384xA CURRENT MODE PWM CONTROLLER PR O D U C T I O N D ATA S H E E T DESCRIPTION The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external components. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The IC includes: A bandgap reference trimmed to ±1% accuracy, an error amplifier, a current sense comparator with internal clamp to 1V, a high current totem pole output stage for fast switching of power MOSFET's, and an externally programmable oscillator to set frequency and maximum duty cycle. The undervoltage lock-out is designed to operate with 250µA typ. start-up current, allowing an efficient bootstrap supply voltage design. Available options for this family of products, such as start-up voltage hysteresis and duty cycle, are summarized below in the Available Options section. The UC184xA family of control ICs is also available in 14-pin SOIC package which makes the Power Output Stage Collector and Ground pins available. PRODUCT HIGHLIGHT COMPARISON OF UC384XA VS. SG384 X DISCHARGE CURRENT SG384x Min. Limit UC384xA TA=25°C SG384x Max. Limit KEY FEATURES s LOW START-UP CURRENT. (0.5mA max.) s TRIMMED OSCILLATOR DISCHARGE CURRENT. (See Product Highlight) p OPT...